Eleven Earth and space scientists say that a recent paper attributing most climate change on Earth to cosmic rays is incorrect and based on questionable methodology. Writing in the January 27 issue of Eos, published by the American Geophysical Union, Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research and colleagues in Canada, France, Germany, Switzerland, and the United States challenge the cosmic ray hypothesis.
In July 2003, astrophysicist Nir Shaviv and geologist Jan Veizer wrote in GSA Today that they had established a correlation between cosmic rays and temperature evolution over hundreds of millions of years. They also claimed that current global warming is not primarily caused by human emissions of carbon dioxide. Their findings have been widely reported in international news media.
According to Rahmstorf, Shaviv and Veizer's analyses--and especially their conclusions--are scientifically ill-founded. The data on cosmic rays and temperature so far in the past are extremely uncertain, he says.
Further, their reconstruction of ancient cosmic rays is based on only 50 meteorites, and most other experts interpret their significance in a very different way, he says.
He adds that two curves presented in the article show an apparent statistical correlation only because the authors adjusted the data, in one case by 40 million years. In short, say the authors of the Eos article, Shaviv and Veizer have not shown that there is any correlation between cosmic rays and climate.
As for the influence of carbon dioxide in climate change, many climatologists were surprised by Shaviv and Veizer's claim that their results disproved that current global warming was caused by human emissions, Rahmstorf says. Even if their analysis were methodologically correct, their work applied to time scales of several million years.
The current climate warming has, however, occurred during just a hundred years, for which completely different mechanisms are relevant, he says. For example, over millions of years, the shifting of continents influences climate, while over hundreds of thousands of years, small changes in Earth's orbit can initiate or terminate ice ages.
But for time periods of years, decades, or centuries, these processes are irrelevant. Volcanic eruptions, changes in solar activity, and the concentration of greenhouse gases, as well as internal oscillations of the climate system, are crucial on this scale.
The 11 authors of the Eos article affirm that the strong increase of carbon dioxide and some other greenhouse gases in the atmosphere due to manmade emissions is most probably the main cause of the global warming of the last few decades.
The most important physical processes are well understood, they say, and model calculations as well as data analyses both come to the conclusion that the human contribution to the global warming of the 20th century was dominant.
Potsdam Institute for Climate Impact Research
Subscribe To SpaceDaily Express
Catch A Falling Ray From Ancient Times
Baton Rouge - Jan 19, 2004
The mention of Argentina conjures any number of exotic or dramatic images .. Eva Peron .. dancing the tango .. gauchos riding the plains .. falling high-energy cosmic rays.
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.|